Method of forming luminous grids



Dec. 15, 1936. J. J. sHlvELY ET Al.

A METHOD OF FORMING LUMINOUS GRIDS Fil'ed May 25, 1935 mw NN QN NN a k fu \m .wNNNN m E mm, k

INVENTORS dohn cl Shiva/ y BY Miles Pennybacker' ATTORN EY Patented Dec. 15, 1936 UNITED STATES PATENT OFFICE John J. Shively, New York,..N. Y., and Miles iPennybacker, West Orange, N. J., assignors to Neosign Corporation, a corporation of Delaware Application`-May 23, 1935, Serial No'. 23,042

1 Claim.

This invention relates to methods of forming luminous grids.

An object of the invention is to provide an improved method of forming grids suitable for use in luminous tube signs and the like.

A further object is to provide a method adapted to the forming of grids of the above type comprising .two or more -parallel legs connected by a unitary return bend or bends.

A still further yobject is `to provide a method of forming grids of the above type in which all the legs lie in the Same plane.

Another purpose is the provision of a method to accurately space the legs while maintaining them in the same plane.

A further object is the provision of a method to compensate for the distortion of the bends upon cooling, thereby insuring parallelism of the legs.

Other objects and advantages will appear in the following description in connection with the attached drawing, in which:

Figure 1 shows a typical grid produced in .accordance with the'method'hereinafter described;

Figure 2 is a cross section ofthe same on the line 2-2, Figure 1;

Figure 3 shows a plan view `of the apparatus in use illustrating a step in the method;

Figure 4 is a cross sectional View of the same on the line 4 4, Figure 3;

Figure 5 is a View similar to Figure 3 but .illustrating a subsequent step in the method; and

Figure 6 is a fragmental View showing the means of compensating .for distortion of the material when cooling.

Referring to Figure 1, .a grid ID `is shown having a plurality of parallel legs II, I2, I3, I4, I5,

Y I6 and IFI connected Lby ,return bends, the grid being vformed of continuous tubing terminating in housings I8 and I9 containing the usual electrodes.

A grid of this type formed of glass tubing is suitable for use in the changeable neon sign fully described and claimed in copending application Serial No. 22,333, filed May 20, 1935. In such signs, the grid is clamped against the flat surface of a sheet of glass, the surface being represented by the plane B-B, Figure 2. It is obvious that for this purpose the grid I0 must be initially formed so as to be flat on the side intended to contact the surface B-B, as otherwise when clamped the grid will be subjected to bending and torsional stresses which may result in breakage.

In such signs it is also important that the center distances between adjacent legs, represented-.in Figure 1 byu?, a2, a3, a4, a5 and a6, .be

substantially equal. It yhas heretofore been attempted to :form such grids entirely .by hand, which process is slow, laborious, and requires so high a degree of rskill as to make it commercially impractical. It has also been attempted to secure parallelism and even spacing of legs by forming them around .a jig of .such dimension that it :occupied theexact space between adjacent tube Walls. This `method has also proved commercially impractical, due to the fact that in tubing .commercially available considerable variations exist :above or below the nominal diameter of the tube. When such tube is-formed around the type vof jig described, an oversize diameter results -i-n an oversized center distance between legs, while van undersized diameter similarly gives van under-sized center distance.

Theseimproper center distances are cumulative asthe ygrid `is formed, `and when completed the grid .does noty t 4the Kframe for which it is designed and is consequently unsuitable for use.

Eiorts have been made to .remedy the above defect by pressing adjacent legs i-nto vparallel V--shaped depressions. This method has also been unsuccessful due to the .fact that lslight irregularities in the tube used in forming a single vgrid have caused the tube to sink to varying depths in the V grooves, .thus .destroying the flatnessy of the grid.

It has further been found that when yadjacent legs have been disposed in parallel relation'while the glass in ithe bend vis hot, the bend 'in cooling -distorts so as lto draw the adjacent legs inward at'z'their ends opposite the bend.

By the use of the present invention, grids maybe formedfromtubing of commercial deviation from nominal diameter, but in which the legs are substantially parallel and evenly spaced at a predetermined center distance, and in which one side of the grid is readily maintained in a dat plane.

Referring to Figures 3 to 6 inclusive, the numeral 2D indicates a platen having its flat upper surface 2| composed of a suitable heat resistant material such as asbestos composition.

Rails 22 and 23, which may be in the form of angle strips, are secured to the surface 2| of platen 20, and have similarly directed surfaces 24 and 25 perpendicular thereto. Rail 23 may be pivotally secured to 2I at 26 and has at its other end a clamping screw 21 extending downward through a slot 28 in platen 2D and engaging a bottom unit 29.

The rail 23 may thus be set at a small variable angle 3l), Figure 6, from a position parallel with rail 22 and clamped in its angular position by means of the screw 2l. The ends 3| and 32 of the rails 22 and 23 remote from the clamping screw 2l,- are spaced so as to retain the surfaces 2t and 25 spaced substantially the desired center distance c apart at this point.

The amount of distortion in cooling which occurs with tubing of a given nominal diameter, wall thickness and sharpness of bend is deter-v mined experimentally and the compensating angle 30 is set accordingly.

In forming a grid I 8, a length of tubing is rst heated at the point to be bent and a return bend such as 33, Figure 3, is made of approximately the sharpness desired. During the bending the tube is subjected to internal air pressure or blown in the usual manner to prevent collapse. While the bend is still plastic the legs such as I3 and i4, Figure 3, are placed against the rail surfaces 24 and 25 with the bend 33 adjacent the ends 3l and 32 and are pressed diagonally against 24, 25 and the platen surface 2| as shown by arrows in Figure 4. The legs I3 and I 4 are thus placed in the same horizontal plane, while their vertical planes correspond to the angle 30.

The diagonal pressure is then removed and the bend 33 allowed to cool, during which process the distortion draws the legs into parallelism. The unit is now removed from the forming device, turned horizontally through 180 degrees, and a second bend 34 made as described above. The unit is again placed in the form, the leg I4 being pressed against the vsurface 25 and the newly directed leg I5 being pressed against surface 24 as shown in Figure 5. All legs are pressed downward against the platen surface 2l at the same time, thus bringing their lower surfaces in the same plane. The bend 34 is allowed to cool, bringing tube I5 parallel to I4, and the above process is repeated until the required number of bendsrhas been completed. The electrode housings I8 and I9 are then fused to the extremities of the grid and directedv in any desired manner. In Figure 2 the electrode I8 is shown with its lower surface in the plane B-B, but it will be understood that for some purposes the electrodes may be otherwise directed, though the active tubes of the grid are maintained in the plane B-B by the method described. After the housings have been attached the grid is evacuated, charged with the desired gas and sealed at any convenient point such as 35, Figure 1.

Guide lines 36 and 31 may be provided on the surface 2I to aid the operator in maintaining the required over-all length of the grid.

From the above description, it is obvious that the invention provides a practical method of commercially forming grids of the type described.

Proper center distances are maintained auto matically being governed by the distance a between the similarly directed surfaces 24 and 25 at points SI and 32. Flatness of the grid is assured by the pressure noted against the surface 2 I, and parallelism is automatically secured by the pre-setting of the angle 30. A high commercial degree of accuracy is thus attained, and cheap and rapid production is made possible, especially as one operator may maintain several grids in process at the same time, heating and making bends while others are cooling.

The invention as noted, is principally directed to the forming of grids having parallel legs, but it is obvious that it may also be used for forming units having legs 4directed at any desired angle by placing the guides at the proper compensating angle of deviation from the desired angle.

While the invention has been described in its preferred manner it is not limitedto the precise structures and sequences set forth, as various modications may be made without departing from the scope of the appended claim.

What is claimed is:

That method of forming a continuous tubular grid which comprises heating a portion of a glass tube to plasticity, bending said portion through an angle of substantially 18() degrees whereby two adjacent legs are formed while applying an internal gaseous pressure to said tube to prevent collapse of said portion, pressing said legs against a common plane surface and against similarly directed separate plane surfaces arranged perpendicularly to same common plane surface in spaced relation while retaining said bent portion in a state of plasticity, one of said separate plane surfaces being arranged at a predetermined angle to the other, allowing said bent portion to cool whereby the distortion thereof may draw said legs through said-predetermined angle into parallelism, removing said tube from said surfaces, heating and bending a second portion of said tube in the manner described and thereby forminga third leg adjacent one of said rst legs, 'revolving said tube horizontally through substantially 180 degrees, pressing all said legs against said common plane surface and said newly formed leg and its adjacent leg against said separate surfaces in the manner described, and repeating the last named ve steps until the required number of legs have been formed.

JOI-IN J. SHIVELY. MILES PENNYBACKER. 

